Image decoding method and image decoding apparatus

ABSTRACT

An image decoding method includes: obtaining, from a bitstream, a first temporal motion vector prediction flag, which is a temporal motion vector prediction flag indicating whether or not temporal motion vector prediction is to be used, indicating that temporal motion vector prediction is not to be used on a first picture; decoding the first picture without using the temporal motion vector prediction; and decoding a second picture which follows the first picture in decoding order, with referring to a motion vector of a picture preceding the first picture in decoding order being prohibited.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/905,724,filed May 30, 2013, which is a continuation application of PCTInternational Patent Application No. PCT/JP2013/000465 filed on Jan. 29,2013, designating the United States of America, which is based on andclaims priority of U.S. Provisional Patent Application No. 61/594,718filed on Feb. 3, 2012. The entire disclosures of the above-identifiedapplications, including the specifications, drawings and claims areincorporated herein by reference in their entirety.

FIELD

The present disclosure relates to an image coding method and an imagedecoding method.

BACKGROUND

In state of the art coding schemes such as H.264/MPEG-4 AVC and thenext-generation High-Efficiency Video Coding (HEVC), images and imagecontent are coded or decoded using inter prediction which makes use of apreviously coded or decoded reference picture. In this manner, in theseimage coding schemes, information redundancy across temporallyconsecutive pictures is exploited (for example, see Non PatentLiterature (NPL) 1).

CITATION LIST Non Patent Literature

[NPL 1] ISO/IEC 14496-10 “MPEG-4 Part 10 Advanced Video Coding”

SUMMARY Technical Problem

Improvement of robustness is desired from such an image coding methodand image decoding method.

One non-limiting and exemplary embodiment provides an image codingmethod and an image decoding method that are capable of improvingrobustness.

Solution to Problem

In order to achieve the aforementioned object, an image decoding methodaccording to an aspect of the present disclosure includes: (A)obtaining, from a bitstream, a first temporal motion vector predictionflag, which is a temporal motion vector prediction flag indicatingwhether or not temporal motion vector prediction is to be used,indicating that temporal motion vector prediction is not to be used on afirst picture; (B) decoding the first picture without using the temporalmotion vector prediction; and (C) decoding a second picture whichfollows the first picture in decoding order, with referring to a motionvector of a picture preceding the first picture in decoding order beingprohibited.

It should be noted that general and specific aspects described above maybe implemented using a system, a method, an integrated circuit, acomputer program, or a computer-readable recording medium such as aCD-ROM, or any combination of systems, methods, integrated circuits,computer programs, or computer-readable recording media.

Additional benefits and advantages of the disclosed embodiments will beapparent from the Specification and Drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the Specification and Drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

Advantageous Effects

The present disclosure can provide an image coding method and an imagedecoding method which are capable of improving robustness.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

FIG. 1 is a block diagram of an image coding apparatus according toEmbodiment 1.

FIG. 2 is a flowchart of the image coding method according to Embodiment1.

FIG. 3 is a flowchart of the image coding method according to Embodiment1.

FIG. 4A is a flowchart of the image coding method according toEmbodiment 1.

FIG. 4B is a diagram for describing the image coding method according toEmbodiment 1.

FIG. 4C is a diagram for describing the image coding method according toEmbodiment 1.

FIG. 5 is a flowchart of a modification of the image coding methodaccording to Embodiment 1.

FIG. 6 is a diagram showing an exemplary configuration of a codedbitstream according to Embodiment 1.

FIG. 7 is a block diagram of an image decoding apparatus according toEmbodiment 1.

FIG. 8 is a flowchart of an image decoding method according toEmbodiment 1.

FIG. 9 is a flowchart of the image decoding method according toEmbodiment 1.

FIG. 10 is a diagram of an overall configuration of a content providingsystem for implementing content distribution services.

FIG. 11 is a diagram of an overall configuration of a digitalbroadcasting system.

FIG. 12 is a block diagram showing an example of a configuration of atelevision.

FIG. 13 is a block diagram showing an example of a configuration of aninformation reproducing/recording unit that reads and writes informationfrom or on a recording medium which is an optical disk.

FIG. 14 is a diagram showing an example of a configuration of arecording medium that is an optical disk.

FIG. 15A is a diagram showing an example of a cellular phone.

FIG. 15B is a block diagram showing an example of a configuration of acellular phone.

FIG. 16 is a diagram showing a structure of multiplexed data.

FIG. 17 is a diagram schematically illustrating how each stream ismultiplexed in multiplexed data.

FIG. 18 is a diagram showing in more detail how a video stream is storedin a stream of PES packets.

FIG. 19 is a diagram showing a structure of TS packets and sourcepackets in the multiplexed data.

FIG. 20 is a diagram illustrating a data structure of a PMT.

FIG. 21 is a diagram showing an internal structure of multiplexed datainformation.

FIG. 22 is a diagram showing an internal structure of stream attributeinformation.

FIG. 23 is a diagram showing steps for identifying video data.

FIG. 24 is a block diagram illustrating an example of a configuration ofan integrated circuit for implementing the moving picture coding methodand the moving picture decoding method according to each of embodiments.

FIG. 25 is a diagram showing a configuration for switching betweendriving frequencies.

FIG. 26 is a diagram showing steps for identifying video data andswitching between driving frequencies.

FIG. 27 is a diagram showing an example of a look-up table in whichvideo data standards are associated with driving frequencies.

FIG. 28A is a diagram illustrating an example of a configuration forsharing a module of a signal processing unit.

FIG. 28B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENTS

(Underlying Knowledge Forming Basis of the Present Disclosure)

The inventors have observed the occurrence of the following problems inrelation to the prior art.

An image decoding apparatus identifies a reference picture used in theinter prediction of a prediction unit (a M×N sample block, etc.), byusing a reference index. The reference index is an index that isassigned to each of one or more reference pictures included in areference picture list. Furthermore, the reference picture list is anordered list indicating one or more reference pictures. Furthermore, thereference index is uniquely associated with a reference picture in thedecoded picture buffer (DPB).

In the state of the art image coding schemes, temporal prediction ofmotion vectors is performed. The motion vectors of a target sample blockare predicted from motion vectors of one or more previously coded sampleblocks included in a co-located reference picture. The co-locatedreference picture is selected from among available reference pictures byusing a predetermined scheme. For example, the first reference pictureis selected, as the co-located reference picture, from among referencepictures included in a predetermined reference picture list (such as thereference picture list 0).

In applications requiring transmission of images using irreversiblecompression, temporal motion vector prediction is susceptible toerroneous prediction of motion vector when the co-located referencepicture is lost or contains errors. In the conventional HEVC imagecoding scheme, a marking flag is introduced in a picture parameter set(PPS) to mark all pictures included in the decoder picture buffer (DPB)as “unused for temporal motion vector prediction”. This marking processis performed when a slice refers to a PPS having a marking flagindicating “TRUE”.

The inventors have observed that, in this scheme, there is the problemthat when the slice on which marking is to be performed is lost orcontains error, a video decoder cannot perform the intended markingprocess and subsequent synchronization between encoder and decoder. Assuch, the aforementioned scheme for disabling temporal motion vectorprediction is not robust.

In the embodiments, methods that improve error robustness in an imagecoding method and an image decoding method that disable temporal motionvector prediction shall be described. The image coding method and imagedecoding method according to the embodiments can eliminate the processof marking reference pictures as “unused for temporal motion vectorprediction”, thereby eliminating the error susceptibility in theaforementioned scheme. The advantageous effect of the embodiments isimproving error robustness of temporal motion vector prediction.

An image coding method according to an aspect of the embodimentsincludes: (A) selecting a first picture from plural pictures; (B)setting a first temporal motion vector prediction flag which isassociated with the first picture and is a temporal motion vectorprediction flag indicating whether or not temporal motion vectorprediction is to be used, to indicate that the temporal motion vectorprediction is not to be used, and coding the first temporal motionvector prediction flag; (C) coding the first picture without using thetemporal motion vector prediction; and (D) coding a second picture whichfollows the first picture in coding order, with referring to a motionvector of a picture preceding the first picture in coding order beingprohibited.

Accordingly, the second picture following the first picture isprohibited from referring to a motion vector of a picture preceding thefirst picture. Accordingly, the image coding method is capable ofpreventing the propagation of error across the first picture, and isthus capable of improving robustness.

For example, a temporal level may be set to each of the pictures, and,in step (A), a picture having a highest temporal level may be selectedas the first picture, from among the pictures.

Accordingly, a picture having a high priority is set as the firstpicture. This can more appropriately prevent error propagation.

For example, step (D) may include: (D1) judging whether or not thesecond picture has a co-located reference picture which precedes thefirst picture in coding order; (D2) when the second picture has aco-located reference picture which precedes the first picture in codingorder: (i) setting a second temporal motion vector prediction flag,which is a temporal motion vector prediction flag associated with thesecond picture, to indicate that the temporal motion vector predictionis not to be used; (ii) coding the second temporal motion vectorprediction flag; and (iii) coding the second picture without using thetemporal motion vector prediction; and (D3) when the second picture doesnot have a co-located reference picture which precedes the first picturein coding order: (i) setting the second temporal motion vectorprediction flag to indicate that the temporal motion vector predictionis to be used or indicate that the temporal motion vector prediction isnot to be used; (ii) coding the second temporal motion vector predictionflag; and (iii) coding the second picture using or without using thetemporal motion vector prediction.

For example, step (D) may include: (D1) judging whether or not thesecond picture precedes the first picture in display order; (D2) judgingwhether or not the second picture has a co-located reference picturewhich precedes the first picture in coding order or in display order;(D3) when the second picture follows the first picture in display orderand has a co-located reference picture which precedes the first picturein coding order or display order: (i) setting a second temporal motionvector prediction flag, which is a temporal motion vector predictionflag associated with the second picture, to indicate that the temporalmotion vector prediction is not to be used; (ii) coding the secondtemporal motion vector prediction flag; and (iii) coding the secondpicture without using the temporal motion vector prediction; and (D4)when the second picture precedes the first picture in display order, orwhen the second picture follows the first picture in display order andhas a co-located reference picture which precedes the first picture incoding order or display order: (i) setting the second temporal motionvector prediction flag, which is the temporal motion vector predictionflag associated with the second picture, to indicate that the temporalmotion vector prediction is not to be used; (ii) coding the secondtemporal motion vector prediction flag; and (iii) coding the secondpicture without using the temporal motion vector prediction.

For example, in step (B), the first temporal motion vector predictionflag indicating that the temporal motion vector prediction is not to beused may be written into a header for each slice included in the firstpicture.

Accordingly, the first picture can be set by using, on a slice basis, aflag indicating whether or not temporal motion vector prediction is tobe used. With this, improvement of robustness can be realized whilesuppressing an increase in the amount of data of the coded bit stream.

For example, the image coding method may further include: (E) creating afirst list indicating plural motion vector predictors that include atemporal motion vector predictor derived from a motion vector of aco-located reference picture, when the temporal motion vector predictionflag indicates that the temporal motion vector prediction is to be used;and (F) creating a second list indicating plural motion vectorpredictors that do not include the temporal motion vector predictor,when the temporal motion vector prediction flag indicates that thetemporal motion vector prediction is not to be used.

Accordingly, the amount of data when temporal motion vector predictionis not to be used can be reduced.

Furthermore, an image decoding method according to an aspect of theembodiments includes: (A) obtaining, from a bitstream, a first temporalmotion vector prediction flag, which is a temporal motion vectorprediction flag indicating whether or not temporal motion vectorprediction is to be used, indicating that temporal motion vectorprediction is not to be used on a first picture; (B) decoding the firstpicture without using the temporal motion vector prediction; and (C)decoding a second picture which follows the first picture in decodingorder, with referring to a motion vector of a picture preceding thefirst picture in decoding order being prohibited.

Accordingly, the second picture following the first picture isprohibited from referring to a motion vector of a picture preceding thefirst picture. Accordingly, the image decoding method is capable ofpreventing the propagation of error across the first picture, and isthus capable of improving robustness.

For example, a temporal level may be set to each of plural pictures, andthe first picture may be a picture having a highest temporal level amongthe pictures.

Accordingly, a picture having a high priority is set as the firstpicture. This can more appropriately prevent error propagation.

For example, in step (A), the first temporal motion vector predictionflag indicating that the temporal motion vector prediction is not to beused may be obtained from a header of each slice included in the firstpicture.

Accordingly, the first picture can be set by using, on a slice basis, aflag indicating whether or not temporal motion vector prediction is tobe used. With this, improvement of robustness can be realized whilesuppressing an increase in the amount of data of the coded bit stream.

For example, the image decoding method may further include: (D) creatinga first list indicating plural motion vector predictors that include atemporal motion vector predictor derived from a motion vector of aco-located reference picture, when the temporal motion vector predictionflag indicates that the temporal motion vector prediction is to be used;and (E) creating a second list indicating plural motion vectorpredictors that do not include the temporal motion vector predictor,when the temporal motion vector prediction flag indicates that thetemporal motion vector prediction is not to be used.

Accordingly, the amount of data when temporal motion vector predictionis not to be used can be reduced.

Furthermore, an image coding apparatus according to an aspect of theembodiments includes: a setting unit configured to select a firstpicture from plural pictures and set a first temporal motion vectorprediction flag which is associated with the first picture and is atemporal motion vector prediction flag indicating whether or nottemporal motion vector prediction is to be used, to indicate that thetemporal motion vector prediction is not to be used; and a coding unitconfigured to (i) code the first temporal motion vector prediction flag,(ii) code the first picture without using the temporal motion vectorprediction, and (iii) code a second picture which follows the firstpicture in coding order, with referring to a motion vector of a picturepreceding the first picture in coding order being prohibited.

According to this configuration, the second picture following the firstpicture is prohibited from referring to a motion vector of a picturepreceding the first picture. Accordingly, the image coding apparatus iscapable of preventing the propagation of error across the first picture,and is thus capable of improving robustness.

Furthermore, an image decoding apparatus according to an aspect of theembodiments includes: an obtaining unit configured to obtain, from abitstream, a first temporal motion vector prediction flag, which is atemporal motion vector prediction flag indicating whether or nottemporal motion vector prediction is to be used, indicating thattemporal motion vector prediction is not to be used on a first picture;and a decoding unit configured to (i) decode the first picture withoutusing the temporal motion vector prediction, and (ii) decode a secondpicture which follows the first picture in decoding order, withreferring to a motion vector of a picture preceding the first picture indecoding order being prohibited.

According to this configuration, the second picture following the firstpicture is prohibited from referring to a motion vector of a picturepreceding the first picture. Accordingly, the image decoding apparatusis capable of preventing the propagation of error across the firstpicture, and is thus capable of improving robustness.

Furthermore, an image coding and decoding apparatus according to anaspect of the embodiments may include the image coding apparatus and theimage decoding apparatus.

It should be noted that general and specific aspects described above maybe implemented using a system, a method, an integrated circuit, acomputer program, or a computer-readable recording medium such as aCD-ROM, or any combination of systems, methods, integrated circuits,computer programs, or computer-readable recording media.

Hereinafter, embodiments of the present disclosure shall be describedwith reference to the Drawings.

It is to be noted that each of the embodiments described below shows ageneral or specific example. The numerical values, shapes, materials,structural elements, the arrangement and connection of the structuralelements, steps, the processing order of the steps etc. shown in thefollowing exemplary embodiments are mere examples. Therefore, among thestructural elements in the following exemplary embodiments, structuralelements not recited in any one of the independent claims defining themost generic concept are described as arbitrary structural elements.

Furthermore, in the subsequent description, there are cases where codingis used to mean encoding.

Embodiment 1

[Coding Apparatus]

First, a configuration of an image coding apparatus according to thisembodiment shall be described. FIG. 1 is a block diagram showing aconfiguration of an image coding apparatus 100 according to thisembodiment.

The image coding apparatus 100 shown in FIG. 1 codes an input image 120(input image bitstream) on a block basis to generate a coded bitstream132. The image coding apparatus 100 includes a subtractor 101, anorthogonal transform unit 102, a quantization unit 103, an inversequantization unit 104, an inverse orthogonal transform unit 105, anadder 106, a block memory 107, a frame memory 108 (picture memory), anintra prediction unit 109, an inter prediction unit 110, a switchingunit 111, a variable-length coding unit 112 (entropy coding unit), and acontrol unit 113.

The subtractor 101 subtracts a predicted image 131 from the input image120 to generate a residual signal 121. The orthogonal transform unit 102transforms the residual signal 121 into frequency coefficients togenerate transform coefficients 122. The quantization unit 103 quantizesthe transform coefficients 122 to generate quantized coefficients 123.The variable-length coding unit 112 performs variable-length coding(entropy coding) on the quantized coefficients 123 to generate the codedbitstream 132.

The inverse quantization unit 104 inverse-quantizes the quantizedcoefficients 123 to generate transform coefficients 124. The inverseorthogonal transform unit 105 performs inverse frequency transform onthe transform coefficients 124 to generate a residual signal 125. Theadder 106 adds the residual signal 125 to the predicted image 131 togenerate a decoded image 126. The decoded image 126 is stored in theblock memory 107 as an image signal 127, and stored in the frame memory108 as an image signal 128. The image signals 127 and 128 are used insubsequent prediction processing.

The intra prediction unit 109 performs intra prediction using the imagedata 127 stored in the block memory 107, to generate a predicted image129. For example, the intra prediction unit 109 detects, from processedimage regions included in a processing target image, an image regionthat is most similar to a processing target image region. The interprediction unit 110 performs inter prediction using the image signal 128stored in the frame memory 108, to generate a predicted image 130. Forexample, the inter prediction unit 110 detects an image region includedin another processed image and which is most similar to the processingtarget image region. The switching unit 111 selects one of the predictedimages 129 and 130, and outputs the selected predicted image as thepredicted image 131.

The control unit 113 judges whether or not to use temporal motion vectorprediction for the inter prediction of the processing target slice, andoutputs a temporal motion vector prediction flag 133 which is a signalindicating the judgment result to the inter prediction unit 110 and thevariable-length coding unit 112. The inter prediction unit 110 performsinter prediction using or without using a temporal motion vectorpredictor, based on the judgment result. Furthermore, thevariable-length coding unit 112 generates the coded bitstream 132 whichincludes the temporal motion vector prediction flag 133. Furthermore,temporal motion vector prediction is processing in which motion vectorprediction is performed using a motion vector included in anotherpicture, as a motion vector predictor.

[Coding Process]

Next, the operation of the above-described image coding apparatus 100shall be described.

FIG. 2 is a flowchart of the image coding process according to thisembodiment.

First, the image coding apparatus 100 writes plural reference picturelist ordering parameters into a slice header of a slice to specify theorder of reference pictures included in one or more reference picturelists and which are to be used for inter prediction of the slice (S101).Here, a reference picture (such as the first reference picture) in apredetermined location in a certain reference picture list (such as thereference picture list 0) indicates the co-located reference picture.

Next, the image coding apparatus 100 writes a temporal motion vectorprediction flag indicating whether or not temporal motion vectorprediction is to be used in the inter prediction of a slice, into theslice header (S102). Next, the image coding apparatus 100 judges whetherthe temporal motion vector prediction flag indicates that temporalmotion vector prediction is to be used or is not to be used (S103). Thevalue of the flag is, for example, “0” when temporal motion vectorprediction is not to be used, and is “1” when temporal motion vectorprediction is to be used.

When the flag indicates that temporal motion vector prediction is to beused (Yes in S104), the image coding apparatus 100 creates a first listof motion vector predictors that include at least one temporal motionvector predictor derived from a motion vector of the co-locatedreference picture (S105). Next, the image coding apparatus 100 selects,from the first list, a motion vector predictor for the processing targetsample block included in the slice (S106). Next, the image codingapparatus 100 writes a first parameter (motion vector predictorselection parameter) indicating the selected motion vector predictorinto the coded bitstream 132 (S107).

On the other hand, when the flag indicates that temporal motion vectorprediction is not to be used (No in S104), the image coding apparatus100 creates a second list of motion vector predictors that do notinclude the temporal motion vector predictor (S108). Next, the imagecoding apparatus 100 selects, from the second list, a motion vectorpredictor for the processing target sample block included in the slice(S109). Next, the image coding apparatus 100 writes a second parameter(motion vector predictor selection parameter) indicating the selectedmotion vector predictor into the coded bitstream 132 (S110).

After step S107 or S110, the image coding apparatus 100 performs motioncompensated inter prediction using the motion vector predictor selectedin step S106 or step S109 to thereby generate a predicted sample block(predicted image 131) (S111). Next, the image coding apparatus 100subtracts the predicted sample block (predicted image 131) from theoriginal sample block (input image 120) to thereby generate a residualsample block (residual signal 121) (S112). Then, the image codingapparatus 100 codes the residual sample block corresponding to thetarget block to thereby generate the coded bitstream 132 (S113).

Here, by way of the temporal motion vector prediction flag, a singleslice is controlled independently of other slices. Furthermore, theimage coding apparatus 100 does not perform marking on a referencepicture in the DPB. Furthermore, in this embodiment, the value of thetemporal motion vector prediction flag may be different for pluralslices within the same picture.

Furthermore, in this embodiment, the number of motion vector predictorsis different between the first list and second list of motion vectorpredictors, and the number of predictors in the second list is 1 lessthan that in the first list. Furthermore, in both lists, motion vectorpredictors other than the temporal motion vector predictors are thesame. In the coded bitstream 132, different bit representations may beused for the first parameter and second parameter which represent theselected motion vector predictor. For example, truncated unaryrepresentation having different maximum values in the arithmetic codingbinarization or in the variable length coding may be used.

It should be noted that the number of motion vector predictors in thefirst list and the second list may be the same. In this case, in placeof the temporal motion vector prediction predictor, the second listincludes a non-temporal motion vector predictor that is not present inthe first list. The non-temporal motion vector predictor is temporallyindependent, that is, derived without using motion vectors from areference picture. An example of the non-temporal motion vectorpredictor is a spatial motion vector predictor derived using one or moreneighboring blocks in the same picture as the target block. It should benoted that the non-temporal motion vector predictor may be a zero motionvector predictor having horizontal motion vector components and verticalmotion vector components equal to zero.

Hereinafter, another example of the coding process according to thisEmbodiment shall be described. FIG. 3 is a flowchart of a coding processfor coding plural pictures, according to this embodiment.

First, the image coding apparatus 100 selects, from plural coding targetpictures, a start picture for temporal motion vector prediction refresh(S121). Temporal motion vector prediction refresh means that propagationof motion vector prediction dependency is terminated at the startpicture.

Here, the image coding apparatus 100 does not use pictures preceding thestart picture for temporal motion vector prediction in the coding of allpictures following the start picture in coding order. Temporal motionvector prediction refresh provides, in the coded bitstream 132, recoverypoints at which reconstruction errors due to temporal motion vectorprediction mismatch can be corrected. With this, error robustness isimproved.

Next, the image coding apparatus 100 codes all the slices included inthe start picture. Furthermore, the image coding apparatus 100 sets thetemporal motion vector prediction flags of all slices included in thestart picture to indicate that “temporal motion vector prediction is notto be used” (e.g., flag value “0”) (S122). In other words, temporalmotion vector prediction will not be used for all the slices included inthe start picture.

Next, the image coding apparatus 100 judges whether or not a sliceincluded in a subsequent picture which follows the start picture incoding order has a co-located reference picture that precedes the startpicture in coding order (S123).

When the co-located reference picture of the slice included in thesubsequent picture precedes the start picture (Yes in S124), the imagecoding apparatus 100 codes the slice included in the subsequent picture.At this time, the image coding apparatus 100 sets the temporal motionvector prediction flag for the slice of the subsequent picture toindicate that “temporal motion vector prediction is not to be used”(e.g., flag value “0”) (S125). In other words, temporal motion vectorprediction beyond the start picture in coding order is disabled.

On the other hand, when the co-located reference picture of the slice ofthe subsequent picture does not precede the start picture (i.e., thestart picture or a picture which follows in coding order is theco-located reference picture) (No in S124), the image coding apparatus100 codes the slice of the subsequent picture. At this time, the imagecoding apparatus 100 sets the temporal motion vector prediction flag forthe slice of the subsequent picture to indicate that “temporal motionvector prediction is to be used” (e.g., flag value “1”) or to indicatethat “temporal motion vector prediction is not to be used” (e.g., flagvalue “0”) (S126). In other words, when the co-located reference picturedoes not precede the start picture in coding order, there is the optionof whether or not to use temporal motion vector prediction on the targetslice. Furthermore, in this embodiment, the selection for whether or notto use temporal motion vector prediction is determined based on whetheror not coding efficiency is maximized.

As described above, the image coding apparatus 100 selects the firstpicture (start picture) from among plural pictures, as shown in FIG. 4A(S141).

Next, the image coding apparatus 100 sets a first temporal motion vectorprediction flag associated with the first picture to indicate thattemporal motion vector prediction is not to be used, and codes the firsttemporal motion vector prediction flag (S142). Specifically, the imagecoding apparatus 100 writes the first temporal motion vector predictionflag indicating that temporal motion vector prediction is not to beused, into the headers of all of the slices included in the firstpicture.

Furthermore, the image coding apparatus 100 codes the first picturewithout using temporal motion vector prediction (S143).

Next, the image coding apparatus 100 codes a second picture whichfollows the first picture in coding order, with the referring to amotion vector of a picture preceding the first picture in coding orderbeing prohibited (S144).

Accordingly, since the image coding apparatus 100 can prohibit thesecond picture following the first picture from referring to a motionvector of a picture preceding the first picture in coding order, it ispossible to prevent the propagation of error across the first picture.Therefore, the image coding apparatus 100 is capable of improvingrobustness.

It should be noted that the order of step S142 and step S143 may beinterchanged.

For example, as shown in FIG. 4B, at the time when picture 4 is coded,referring to motion vectors of picture 0 and picture 1 which precedestart picture 2 is prohibited. Furthermore, as shown in FIG. 4C, thesame is true for the case when the coding order and display order(output order) are different. In the example shown in FIG. 4C, at thetime when picture 4 is coded, referring to a motion vector of picture 0which precedes the start picture is prohibited. It should be noted thatin FIG. 4B and FIG. 4C, the picture numbers (picture 0, picture 1, . . .) indicate the coding order.

Here, step S141 and part of S142 are executed by a setting unit includedin the image coding apparatus 100. Furthermore, another part of theaforementioned step S142, and steps S143 and S144 are executed by acoding unit included in the image coding apparatus 100. For example, thesetting unit is included in the control unit 113 shown in FIG. 1.Furthermore, the main function of the coding unit is realized by theinter prediction unit 110, the variable length coding unit 112, and thecontrol unit 113 shown in FIG. 1.

Furthermore, although as a method of prohibiting the subsequent picturewhich follows the start picture from referring to a motion vector of apicture preceding the start picture, a method which does not usetemporal motion vector prediction for the subsequent picture isillustrated here, other methods may be used.

For example, when the co-located reference picture of the subsequentpicture precedes the start picture, the image coding apparatus 100 maychange such co-located reference picture to the start picture or apicture following the start picture.

Furthermore, when the co-located reference picture of the subsequentpicture precedes the start picture, the image coding apparatus 100 maycreate a list (the second list) of motion vector predictors that do notinclude a temporal motion vector predictor, instead of setting thetemporal motion vector prediction flag to indicate that “temporal motionvector prediction is not to be used”. Furthermore, even when creating alist of motion vector predictors that include a temporal motion vectorpredictor, the image coding apparatus 100 may, for example, performcoding without selecting the index assigned to the temporal motionvector predictor, so as not to select the temporal motion vectorpredictor.

Hereinafter, a modification of the coding process according to thisembodiment shall be described. FIG. 5 is a flowchart of a coding processfor coding plural pictures, according to a modification of thisembodiment.

The image coding apparatus 100 selects, from plural pictures, a startpicture for temporal motion vector prediction refresh (S161). Then, theimage coding apparatus 100 codes all the slices included in the startpicture. Furthermore, the image coding apparatus 100 sets the temporalmotion vector prediction flags of all the slices included in the startpicture to indicate that “temporal motion vector prediction is not to beused” (S162).

Next, the image coding apparatus 100 judges whether or not a subsequentpicture which follows the start picture in coding order precedes thestart picture in output order (also commonly called display order)(S163).

When the subsequent picture precedes the start picture in output order(Yes in S164), the image coding apparatus 100 codes a slice of thesubsequent picture. At this time, the image coding apparatus 100 setsthe temporal motion vector prediction flag for the slice of thesubsequent picture to indicate that “temporal motion vector predictionis to be used” (e.g., flag value “1”) or to indicate that “temporalmotion vector prediction is not to be used” (e.g., flag value “0”)(S165). In other words, when the subsequent picture precedes the startpicture in output order, there is the option of whether or not to usetemporal motion vector prediction on the slice of the subsequentpicture. In this embodiment, the selection for whether or not to usetemporal motion vector prediction is determined based on whether or notcoding efficiency is maximized.

On the other hand, when the subsequent picture does not precede thestart picture in output order (i.e., follows the start picture in outputorder) (No in S164), the image coding apparatus 100 judges whether ornot the slice included in the subsequent picture has a co-locatedreference picture that precedes the start picture in either coding orderor output order (S166).

When the co-located reference picture of the slice included in thesubsequent picture precedes the start picture in either the coding orderor output order (Yes in S167), the image coding apparatus 100 codes theslice included in the subsequent picture. At this time, the image codingapparatus 100 sets the temporal motion vector prediction flag for theslice to indicate that “temporal motion vector prediction is not to beused” (e.g., flag value “0”) (S168). In other words, temporal motionvector prediction beyond the start picture in either coding order oroutput order is disabled.

On the other hand, when the co-located reference picture of the sliceincluded in the subsequent picture does not precede the start picture ineither the coding order or output order (No in S167), the image codingapparatus 100 codes the slice included in the subsequent picture. Atthis time, the image coding apparatus 100 sets the temporal motionvector prediction flag for the slice to indicate that “temporal motionvector prediction is to be used” (e.g., flag value “1”) or to indicatethat “temporal motion vector prediction is not to be used” (e.g., flagvalue “0”) (S169). In other words, when the co-located reference picturefollows the start picture in coding order and output order, there is theoption of whether or not to use temporal motion vector prediction on thetarget slice. In this embodiment, the selection for whether or not touse temporal motion vector prediction is determined based on whether ornot coding efficiency is maximized.

Furthermore, in the example of the coding process describe above,normative restrictions are provided as shown below.

The temporal level of a start picture has the highest priority. Anexample of a temporal level having the highest priority is the temporallevel 0 in HEVC video coding scheme, that is, a temporal_id in a NetworkAbstraction Layer (NAL) unit header of the slice is equal to 0.

Here, temporal level (temporal hierarchy) indicates that a picture(slice) having a certain temporal level can refer to information of apicture having the same temporal level or a higher temporal level. Forexample, a picture having the highest temporal level (temporal_id=0) iscoded using only a picture having the highest temporal level. Stateddifferently, the picture having the highest temporal level(temporal_id=0) can be decoded using only a picture having the highesttemporal level.

All slices included in a start picture shall not use temporal motionvector prediction (e.g., flag values set to 0). Therefore, a startpicture is identified as a picture having the highest priority temporallevel (e.g., temporal_id is 0) and the temporal motion vector predictionflag indicates “not to be used” (e.g., flag value is 0).

Any pictures following a start picture shall not use temporal motionvector prediction beyond the start picture as described in FIG. 3 (usingcoding order conditions) or FIG. 5 (using coding order and output orderconditions).

Furthermore, the coded bitstream 132 conforms to the normativeconditions.

An image decoding apparatus according to this embodiment can detectbitstream non-conformances (with respect to the normative restrictions)and arbitrarily perform error handling processes when suchnon-conformances are detected. For example, the image decoding apparatusmay conceal a non-conformant block (or slice) by replacing thenon-conformant block (or slice) with a co-located block (or slice)included in a prior reconstructed picture that precedes the decodingtarget picture and is nearest to the decoding target picture.

[Syntax]

FIG. 6 is a syntax diagram showing a location of the temporal motionvector prediction flag according to this embodiment.

As shown in FIG. 6, reference picture list ordering parameters forspecifying the order of reference pictures in one or more referencepicture lists are located in the slice header. These parametersdetermine the effective or final order of reference picture lists usedfor inter prediction of the slice corresponding to the slice header.Furthermore, these parameters may specify a reordering process to beperformed on one or more initial reference picture lists, or may specifythat the initial reference picture lists are to be used withoutreordering. Here, an initial reference picture list is a referencepicture list created using a predetermined ordered scheme.

Furthermore, a temporal motion vector prediction flag is included in theslice header in the same manner as the reference picture list orderingparameters. The temporal motion vector prediction flag indicates whetheror not temporal motion vector prediction is to be used for the slicecorresponding to the slice header.

A motion vector predictor selection parameter is provided at each ofprediction units. This motion vector predictor selection parameterindicates a single motion vector predictor selected in the interprediction of a prediction unit, from among plural motion vectorpredictors available for inter prediction of the prediction unit.

A temporal level parameter is included in the slice header. As describedabove, the image coding apparatus 100 selects a start picture fortemporal motion vector prediction refresh from among plural pictures,using this temporal level parameter. Specifically, the image codingapparatus 100 selects, as the start picture, a picture having thehighest temporal level among plural pictures.

It should be noted that the reference picture list ordering parametersand the temporal motion vector prediction flag may be included in aheader shared among plural slices included in the same picture. Anexample of such a header is an adaptation parameter set (APS) header.

Slice partitioning is one method for dividing a picture into multiplesub-picture partitions. Therefore, this embodiment may be applied whenother sub-picture partitioning methods such as tile, entropy slice, orwavefront partitioning units are used. In other words, the parametersincluded in a slice header may be included in a header for a sub-pictureunit.

[Advantageous Effect of Coding Invention]

Accordingly, the image coding apparatus 100 according to this embodimentis capable of improving error robustness of inter prediction using atemporal motion vector predictor. Furthermore, the image codingapparatus 100 is capable of improving coding efficiency and flexibilityof inter prediction, as temporal motion vector predictors can be enabledand disabled independently in plural slices included in the samepicture.

[Decoding Apparatus]

Hereinafter, an image decoding apparatus 200 according to thisembodiment shall be described. The image decoding apparatus 200 decodesthe coded bitstream 132 generated by the above-described image codingapparatus 100.

FIG. 7 is a block diagram showing a configuration of the image decodingapparatus 200 according to this embodiment.

The image decoding apparatus 200 decodes a coded bitstream 232 on ablock basis to generate a decoded image 226. Here, the coded bitstream232 is, for example, the coded bitstream 132 generated by theabove-described image coding apparatus 100.

As shown in FIG. 7, the image decoding apparatus 200 includes avariable-length decoding unit 212 (entropy coding unit), an inversequantization unit 204, an inverse orthogonal transform unit 205, anadder 206, a block memory 207, a frame memory 208 (picture memory), anintra prediction unit 209, an inter prediction unit 210, and a switchingunit 211.

The variable-length decoding unit 212 performs variable-length decodingon the coded bitstream 232 to generate quantized coefficients 223. Theinverse quantization unit 204 inverse-quantizes the quantizedcoefficients 223 to generate transform coefficients 224. The inverseorthogonal transform unit 205 performs inverse frequency transform onthe transform coefficients 224 to generate a residual signal 225. Theadder 206 adds up the residual signal 225 and a predicted image 231 togenerate a decoded image 226. The decoded image 226 is, for example,outputted to a display unit. Furthermore, the decoded image 226 isstored in the block memory 207 and the frame memory 208, as imagesignals 227 and 228, respectively, for subsequent prediction.

The intra prediction unit 209 performs intra prediction using the imagesignal 227 stored in the block memory 207, to generate a predicted image229. For example, the intra prediction unit 209 detects, from processedimage regions included in a processing target image, an image regionthat is most similar to a processing target image region. The interprediction unit 210 performs inter prediction using the image signal 228stored in the frame memory 208, to generate a predicted image 230. Forexample, the inter prediction unit 210 detects an image region includedin another processed image and which is most similar to the processingtarget image region. The switching unit 211 selects one of the predictedimages 229 and 230, and outputs the selected predicted image as thepredicted image 231.

Furthermore, the variable-length decoding unit 212 obtains, from thecoded bitstream 232, a temporal motion vector prediction flag 233indicating whether or not temporal motion vector prediction is to beused in the inter prediction for the decoding target slice. The interprediction unit 210 performs inter prediction using or without using atemporal motion vector predictor, based on this flag.

[Decoding Process]

Next, the operation of the above-described image decoding apparatus 200shall be described. FIG. 8 is a flowchart of the image decoding processaccording to this embodiment.

First, the image decoding apparatus 200 obtains reference picture listordering parameters from a slice header (S201). Furthermore, the imagedecoding apparatus 200 identifies the order of reference picturesincluded in one or more reference picture lists and which are to be usedfor inter prediction of the slice, according to the reference picturelist order parameters. Here, a reference picture at a predeterminedposition in a certain reference picture list is a co-located referencepicture.

Next, the image decoding apparatus 200 obtains the temporal motionvector prediction flag from the slice header (S202). Next, the imagedecoding apparatus 200 judges whether the temporal motion vectorprediction flag indicates that temporal motion vector prediction is tobe used or is not to be used (S203).

When the flag indicates that temporal motion vector prediction is to beused (Yes in S204), the image decoding apparatus 200 creates a firstlist of motion vector predictors that include at least one temporalmotion vector predictor derived from a motion vector of the co-locatedreference picture (S205). Next, the image decoding apparatus 200 obtainsa first parameter (motion vector predictor selection flag) from thecoded bitstream 232 (S206). The first parameter indicates a motionvector predictor selected from the first list, for a decoding targetsample block included in the slice.

On the other hand, when the flag indicates that temporal motion vectorprediction is not to be used (No in S204), the image decoding apparatus200 creates a second list of motion vector predictors that do notinclude a temporal motion vector predictor (S207). Next, the imagedecoding apparatus 200 obtains a second parameter (motion vectorpredictor selection flag) from the coded bitstream 232 (S208). Here, thesecond parameter indicates a motion vector predictor selected from thesecond list, for the decoding target sample block included in the slice.

After step S206 or S208, the image decoding apparatus 200 performsmotion compensated inter prediction using the motion vector predictorindicated by the first parameter or the second parameter to therebygenerate a predicted sample block (predicted image 231) (S209). Next,the image decoding apparatus 200 decodes a residual sample block(residual signal 225) from the coded bitstream 232 (S210). Lastly, theimage decoding apparatus 200 adds up the predicted sample block(predicted image 231) and the residual sample block (residual signal225) to thereby generate a reconstructed sample block (decoded image226) corresponding to the decoding target block (S211).

Furthermore, the image decoding apparatus 200 according to thisembodiment obtains, from the coded bitstream 232, a first temporalmotion vector prediction flag indicating that temporal motion vectorprediction is not to be used on the first picture (start picture).Specifically, the image decoding apparatus 200 obtains, from the headersof all of the slices included in the first picture, the first temporalmotion vector prediction flag indicating that temporal motion vectorprediction is not to be used.

Next, the image decoding apparatus 200 codes the first picture withoutusing temporal motion vector prediction (S242). Next, the image decodingapparatus 200 codes a second picture which follows the first picture indecoding order, with the referring to a motion vector of a picturepreceding the first picture in decoding order being prohibited (S243).It should be noted that details of these processes is equivalent to theprocesses of the above-described image coding apparatus 100.

Here, step S241 is executed by an obtainment unit included in the imagedecoding apparatus 200. Furthermore, steps S242 and S243 are executed bya decoding unit included in the image decoding apparatus 200. Forexample, the obtainment unit may is included in the variable-lengthdecoding unit 212 shown in FIG. 7. Furthermore, the main function of thedecoding unit is realized by the inter prediction unit 210 shown in FIG.7.

[Advantageous Effect of Decoding Invention]

Accordingly, the image decoding apparatus 200 according to thisembodiment is capable decoding a coded bitstream which is coded withimproved error robustness, flexibility, and coding efficiency of interprediction using a temporal motion vector predictor.

Although an image coding apparatus and an image decoding apparatusaccording to the embodiments have been described thus far, the presentdisclosure is not limited to such embodiments.

Furthermore, the respective processing units included in the imagecoding apparatus and image decoding apparatus according to theabove-described embodiments are typically implemented as an LSI which isan integrated circuit. These processing units may be individuallyconfigured as single chips or may be configured so that a part or all ofthe processing units are included in a single chip.

Furthermore, the method of circuit integration is not limited to LSIs,and implementation through a dedicated circuit or a general-purposeprocessor is also possible. A Field Programmable Gate Array (FPGA) whichallows programming after LSI manufacturing or a reconfigurable processorwhich allows reconfiguration of the connections and settings of thecircuit cells inside the LSI may also be used.

In the respective embodiments, the respective constituent elements areconfigured using dedicated hardware, but may also be implemented byexecuting software programs suited to the respective constituentelements. The respective constituent elements may be implemented throughthe reading and execution of a software program recorded on a recordingmedium such as a hard disk or semiconductor memory by a programexecution unit such as a CPU or a processor.

In addition, the present disclosure may be the aforementioned softwareprogram, or a non-transitory computer-readable recording medium on whichthe aforementioned program is recorded. Furthermore, it should beobvious that the aforementioned program can be distributed via atransmission medium such as the Internet.

Moreover, all numerical figures used in the forgoing description aremerely examples for describing the present disclosure in specific terms,and thus the present disclosure is not limited to the illustratednumerical figures.

Furthermore, the separation of the function blocks in the block diagramsis merely an example, and plural function blocks may be implemented as asingle function block, a single function block may be separated intoplural function blocks, or part of functions of a function block may betransferred to another function block. Furthermore, the functions offunction blocks having similar functions may be processed, in parallelor by time-sharing, by a single hardware or software.

Furthermore, the sequence in which the steps included in theabove-described image coding method and image decoding method areexecuted is given as an example to describe the present disclosure inspecific terms, and thus other sequences are possible. Furthermore, partof the above-described steps may be executed simultaneously (inparallel) with another step.

Although respective exemplary embodiments have been described, the scopeof the Claims of the present application is not limited to suchembodiments. Those skilled in the art will readily appreciate thatvarious modifications may be made in these exemplary embodiments andother embodiments may be obtained by arbitrarily combining constituentelements in the respective embodiments without departing from the novelteachings and advantages of the subject matter of the appended Claims.Therefore, such modifications and other embodiments are included in thepresent disclosure.

Embodiment 2

The processing described in each of embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofembodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image coding apparatus using theimage coding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 10 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 10, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital camera, is capable ofcapturing both still images and video. Furthermore, the cellular phoneex114 may be the one that meets any of the standards such as GlobalSystem for Mobile Communications (GSM) (registered trademark), CodeDivision Multiple Access (CDMA), Wideband-Code Division Multiple Access(W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of embodiments (i.e., the camerafunctions as the image coding apparatus according to an aspect of thepresent disclosure), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the coded data (i.e., functions as the imagedecoding apparatus according to an aspect of the present disclosure).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be integrated intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the video data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 11. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of embodiments (i.e.,data coded by the image coding apparatus according to an aspect of thepresent disclosure). Upon receipt of the multiplexed data, the broadcastsatellite ex202 transmits radio waves for broadcasting. Then, a home-useantenna ex204 with a satellite broadcast reception function receives theradio waves. Next, a device such as a television (receiver) ex300 and aset top box (STB) ex217 decodes the received multiplexed data, andreproduces the decoded data (i.e., functions as the image decodingapparatus according to an aspect of the present disclosure).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording medium ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 12 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast; a modulation/demodulation unit ex302 thatdemodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, respectively (which function as the imagecoding apparatus and the image decoding apparatus according to theaspects of the present disclosure); and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation. Furthermore, the television ex300 includes a control unitex310 that controls overall each constituent element of the televisionex300, and a power supply circuit unit ex311 that supplies power to eachof the elements. Other than the operation input unit ex312, theinterface unit ex317 may include: a bridge ex313 that is connected to anexternal device, such as the reader/recorder ex218; a slot unit ex314for enabling attachment of the recording medium ex216, such as an SDcard; a driver ex315 to be connected to an external recording medium,such as a hard disk; and a modem ex316 to be connected to a telephonenetwork. Here, the recording medium ex216 can electrically recordinformation using a non-volatile/volatile semiconductor memory elementfor storage. The constituent elements of the television ex300 areconnected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 13 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 14 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 12. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 15A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, coded or decoded dataof the received video, the still pictures, e-mails, or others; and aslot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 15B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of embodiments (i.e.,functions as the image coding apparatus according to the aspect of thepresent disclosure), and transmits the coded video data to themultiplexing/demultiplexing unit ex353. In contrast, during when thecamera unit ex365 captures video, still images, and others, the audiosignal processing unit ex354 codes audio signals collected by the audioinput unit ex356, and transmits the coded audio data to themultiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of embodiments (i.e., functions as the imagedecoding apparatus according to the aspect of the present disclosure),and then the display unit ex358 displays, for instance, the video andstill images included in the video file linked to the Web page via theLCD control unit ex359. Furthermore, the audio signal processing unitex354 decodes the audio signal, and the audio output unit ex357 providesthe audio.

Furthermore, similarly to the television ex300, it is possible for aterminal such as the cellular phone ex114 to have 3 types ofimplementation configurations including not only (i) a transmitting andreceiving terminal including both a coding apparatus and a decodingapparatus, but also (ii) a transmitting terminal including only a codingapparatus and (iii) a receiving terminal including only a decodingapparatus. Although the digital broadcasting system ex200 receives andtransmits the multiplexed data obtained by multiplexing audio data ontovideo data in the description, the multiplexed data may be data obtainedby multiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofembodiments can be obtained.

Furthermore, various modifications and revisions can be made to therespective embodiments of the present disclosure described above.

Embodiment 3

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since thestandard to which each of the plurality of the video data to be decodedconforms cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG-2 Transport Stream format.

FIG. 16 illustrates a structure of the multiplexed data. As illustratedin FIG. 16, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary audio to be mixed with the primary audio.

FIG. 17 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 18 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 18 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 18, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 19 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 19. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 20 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 21. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 21, the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 22, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 23 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute informationincluded in the multiplexed data information is obtained from themultiplexed data. Next, in Step exS101, it is determined whether or notthe stream type or the video stream attribute information indicates thatthe multiplexed data is generated by the moving picture coding method orthe moving picture coding apparatus in each of embodiments. When it isdetermined that the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of embodiments, in Step exS102, decoding is performed by the movingpicture decoding method in each of embodiments. Furthermore, when thestream type or the video stream attribute information indicatesconformance to the conventional standards, such as MPEG-2, MPEG-4 AVC,and VC-1, in Step exS103, decoding is performed by a moving picturedecoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard is input, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in the present embodiment can be used inthe devices and systems described above.

Embodiment 4

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 24 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recordingmedium ex215. When data sets are multiplexed, the data should betemporarily stored in the buffer ex508 so that the data sets aresynchronized with each other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present disclosureis applied to biotechnology.

Embodiment 5

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of embodiments isdecoded, it is possible for the processing amount to increase comparedto when video data that conforms to a conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 is decoded. Thus, the LSI ex500 needs to beset to a driving frequency higher than that of the CPU ex502 to be usedwhen video data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 25illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 24.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 24. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. It is possible that the identification information described inEmbodiment 3 is used for identifying the video data. The identificationinformation is not limited to the one described in Embodiment 3 but maybe any information as long as the information indicates to whichstandard the video data conforms. For example, when which standard videodata conforms to can be determined based on an external signal fordetermining that the video data is used for a television or a disk,etc., the determination may be made based on such an external signal.Furthermore, the CPU ex502 selects a driving frequency based on, forexample, a look-up table in which the standards of the video data areassociated with the driving frequencies as shown in FIG. 27. The drivingfrequency can be selected by storing the look-up table in the bufferex508 and in an internal memory of an LSI, and with reference to thelook-up table by the CPU ex502.

FIG. 26 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofembodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, it is possible thatthe voltage to be applied to the LSI ex500 or the apparatus includingthe LSI ex500 is set to a voltage lower than that in the case where thedriving frequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG-4 AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of embodiments, it is possible that thedriving frequency is set in reverse order to the setting describedabove.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of embodiments, it is possible thatthe voltage to be applied to the LSI ex500 or the apparatus includingthe LSI ex500 is set higher. When the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG-4 AVC, and VC-1, it is possible that the voltage tobe applied to the LSI ex500 or the apparatus including the LSI ex500 isset lower. As another example, it is possible that, when theidentification information indicates that the video data is generated bythe moving picture coding method and the moving picture coding apparatusdescribed in each of embodiments, the driving of the CPU ex502 is notsuspended, and when the identification information indicates that thevideo data conforms to the conventional standard, such as MPEG-2, MPEG-4AVC, and VC-1, the driving of the CPU ex502 is suspended at a given timebecause the CPU ex502 has extra processing capacity. It is possiblethat, even when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of embodiments, in the casewhere the CPU ex502 has extra processing capacity, the driving of theCPU ex502 is suspended at a given time. In such a case, it is possiblethat the suspending time is set shorter than that in the case where whenthe identification information indicates that the video data conforms tothe conventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Embodiment 6

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a cellular phone. In order to enable decoding theplurality of video data that conforms to the different standards, thesignal processing unit ex507 of the LSI ex500 needs to conform to thedifferent standards. However, the problems of increase in the scale ofthe circuit of the LSI ex500 and increase in the cost arise with theindividual use of the signal processing units ex507 that conform to therespective standards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 are partly shared. Ex900 in FIG. 28A showsan example of the configuration. For example, the moving picturedecoding method described in each of embodiments and the moving picturedecoding method that conforms to MPEG-4 AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. It is possiblefor a decoding processing unit ex902 that conforms to MPEG-4 AVC to beshared by common processing operations, and for a dedicated decodingprocessing unit ex901 to be used for processing which is unique to anaspect of the present disclosure and does not conform to MPEG-4 AVC. Inparticular, since the aspect of the present disclosure is characterizedby inter prediction, it is possible, for example, for the dedicateddecoding processing unit ex901 to be used for inter prediction, and forthe decoding processing unit to be shared by any or all of the otherprocessing, such as entropy decoding, inverse quantization, deblockingfiltering, and motion compensation. The decoding processing unit forimplementing the moving picture decoding method described in each ofembodiments may be shared for the processing to be shared, and adedicated decoding processing unit may be used for processing unique tothat of MPEG-4 AVC.

Furthermore, ex1000 in FIG. 28B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to an aspect of the present disclosure, a dedicated decodingprocessing unit ex1002 that supports the processing unique to anotherconventional standard, and a decoding processing unit ex1003 thatsupports processing to be shared between the moving picture decodingmethod according to the aspect of the present disclosure and theconventional moving picture decoding method. Here, the dedicateddecoding processing units ex1001 and ex1002 are not necessarilyspecialized for the processing according to the aspect of the presentdisclosure and the processing of the conventional standard,respectively, and may be the ones capable of implementing generalprocessing. Furthermore, the configuration of the present embodiment canbe implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding methodaccording to the aspect of the present disclosure and the moving picturedecoding method in conformity with the conventional standard.

INDUSTRIAL APPLICABILITY

The present disclosure can be applied to an image coding method, animage decoding method, an image coding apparatus, and an image decodingapparatus. For example, the present disclosure can be used ininformation display devices and image-capturing devices such as atelevision, a digital video recorder, a car navigation system, acellular phone, a digital still camera, a digital video camera, and soon.

The invention claimed is:
 1. An image decoding method comprising: (A)obtaining, from a bitstream, a temporal motion vector prediction flagindicating whether or not temporal motion vector prediction is to beperformed on a first picture, the temporal motion vector predictionusing a motion vector of a co-located reference picture; (B) judgingwhether the temporal motion vector prediction flag indicates (i) thetemporal motion vector prediction is to be performed on the firstpicture or (ii) the temporal motion vector prediction is not to beperformed on the first picture; (C-1) when said judging judges that thetemporal motion vector prediction flag indicates the temporal motionvector prediction is not to be performed on the first picture, decodingthe first picture by using inter prediction without performing thetemporal motion vector prediction; (C-2) when said judging judges thatthe temporal motion vector prediction flag indicates the temporal motionvector prediction is to be performed on the first picture, decoding thefirst picture by using the inter prediction including performing thetemporal motion vector prediction; (D-1) when said judging judges thatthe temporal motion vector prediction flag indicates that the temporalmotion vector prediction is not to be performed on the first picture,generating a motion vector prediction list for a second picture, thesecond picture (i) following the first picture in decoding order and(ii) being decoded by using temporal motion vector prediction, themotion vector prediction list (i) including a temporal motion predictionvector derived by using a motion vector of a co-located referencepicture, the co-located reference picture being the first picture and(ii) not including temporal motion prediction vectors derived by usingmotion vectors of all co-located reference pictures preceding the firstpicture in decoding order; (D-2) when said judging judges that thetemporal motion vector prediction flag indicates that the temporalmotion vector prediction is to be performed on the first picture,generating the motion vector prediction list for the second picturewhich includes a temporal motion prediction vector derived by using amotion vector of a co-located reference picture preceding the firstpicture in decoding order; and (E) decoding the second picture by usingthe temporal motion vector prediction using the temporal motionprediction vector selected from the motion vector prediction list,wherein step (C-1) includes (i) creating a second list of motion vectorpredictors that does not include the temporal motion vector predictorderived from the motion vector of the co-located reference picture, (ii)obtaining a second parameter from a bitstream, the second parameterindicating a motion vector predictor included in the second list, and(iii) decoding the first picture using the motion vector predictorindicated by the second parameter, wherein step (C-2) includes (i)creating a first list of motion vector predictors that includes at leastone temporal motion vector predictor derived from the motion vector ofthe co-located reference picture, (ii) obtaining a first parameter froma bitstream, the first parameter indicating a motion vector predictorincluded in the first list, and (iii) decoding the first picture usingthe motion vector predictor indicated by the first parameter, andwherein a number of the motion vector predictors included in the firstlist and a number of the motion vector predictors included in the secondlist are same.
 2. An image decoding apparatus comprising: a processor;and a non-transitory memory having stored thereon executableinstructions, which when executed by the processor, cause the processorto perform: (A) obtaining, from a bitstream, a temporal motion vectorprediction flag indicating whether or not temporal motion vectorprediction is to be performed on a first picture, the temporal motionvector prediction using a motion vector of a co-located referencepicture; (B) judging whether the temporal motion vector prediction flagindicates (i) the temporal motion vector prediction is to be performedon the first picture or (ii) the temporal motion vector prediction isnot to be performed on the first picture; (C-1) when said judging judgesthat the temporal motion vector prediction flag indicates the temporalmotion vector prediction is not to be performed on the first picture,decoding the first picture by using inter prediction without performingthe temporal motion vector prediction; (C-2) when said judging judgesthat the temporal motion vector prediction flag indicates the temporalmotion vector prediction is to be performed on the first picture,decoding the first picture by using the inter prediction includingperforming the temporal motion vector prediction; (D-1) when saidjudging judges that the temporal motion vector prediction flag indicatesthat the temporal motion vector prediction is not to be performed on thefirst picture, generating a motion vector prediction list for a secondpicture, the second picture (i) following the first picture in decodingorder and (ii) being decoded by using temporal motion vector prediction,the motion vector prediction list (i) including a temporal motionprediction vector derived by using a motion vector of a co-locatedreference picture, the co-located reference picture being the firstpicture and (ii) not temporal motion prediction vectors derived by usingmotion vectors of all co-located reference pictures preceding the firstpicture in decoding order; (D-2) when said judging judges that thetemporal motion vector prediction flag indicates that the temporalmotion vector prediction is to be performed on the first picture,generating the motion vector prediction list for the second picturewhich includes a temporal motion prediction vector derived by using amotion vector of a co-located reference picture preceding the firstpicture in decoding order; and (E) decoding the second picture by usingthe temporal motion vector prediction using the temporal motionprediction vector selected from the motion vector prediction list,wherein step (C-1) includes (i) creating a second list of motion vectorpredictors that does not include the temporal motion vector predictorderived from the motion vector of the co-located reference picture, (ii)obtaining a second parameter from a bitstream, the second parameterindicating a motion vector predictor included in the second list, and(iii) decoding the first picture using the motion vector predictorindicated by the second parameter, wherein step (C-2) includes (i)creating a first list of motion vector predictors that includes at leastone temporal motion vector predictor derived from the motion vector ofthe co-located reference picture, (ii) obtaining a first parameter froma bitstream, the first parameter indicating a motion vector predictorincluded in the first list, and (iii) decoding the first picture usingthe motion vector predictor indicated by the first parameter, andwherein a number of the motion vector predictors included in the firstlist and a number of the motion vector predictors included in the secondlist are same.